Written By: Bhavyajyoti Chilukoti | Updated : June 9, 2015 7:44 AM IST
Your doctor might have told you to undergo a blood test and specified that you should fast for at least 10 hours before going for one. You might think that chewing mint after your dinner or sipping a cup of coffee in the morning is ok. But in reality, fasting for less than 10 - 12 hours can affect your test results. Our expert Dr Abha Shroff, chief pathologist and director at Disha Pathology Labs, Mumbai clears all your doubts about fasting.
Why is fasting before certain blood tests necessary?
Fasting means you should not eat/drink any food or drinks, except water for a set period because the nutrients present in food are absorbed into your bloodstream, which in turn affect the parameters being measured.
What will happen if you don t fast for a set period?
The time required for fasting (before going for a blood test) is calculated based on the overall rate of metabolism in a healthy individual, which is around 10-12 hours prior to having your blood drawn. If you don t fast, or fast for a less than the prescribed duration, your test results might be inaccurate. This means that you might have to repeat the test for a proper diagnosis.
Also, some test values change may change depending on the type of food you eat. For example, if you eat lots of sweets, your blood sugar will be high. Hence, to avoid inaccurate readings and improper diagnosis, follow your doctor s instructions without fail.
What other activities or foods you should refrain from before going for a blood test?
In most cases, it is recommended not to drink any juice, tea or coffee, prior to getting tested. However, you may have a few sips of water. Also, do not smoke, chew gum or exercise as these activities may stimulate the digestive system and affect the test results.
What is the best time for a blood test if you are fasting?
You should get your blood test done in the early morning as it minimizes the length of time you need to go without food. Also, in case of diabetes, post-lunch (after eating) blood test is also carried out to determine the changes in your blood sugar levels. Here are 3 tests for diabetes you should know about.
Can you take medicines/nutrient supplements before getting tested?
Ask your doctor if you should continue taking your regular medicines/vitamin and mineral supplements while you are fasting. In some cases, these medications might affect the test leading to an inaccurate diagnosis.
What to do after your blood test is done?
As you are on an empty stomach for more than 12 hours, you might be feeling low on energy. So carry a biscuit packet or a fruit and a bottle of water with you while going for a blood test to satiate your hunger pangs.
Remember these points the next time you go for a blood test that requires fasting. Don't forget to share this page with your family and friends so they can follow the correct procedure before going for a blood test.
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